Pass lock security system

I have a 2001 chevy blazer...for unknown reason i will be driving and it will just shut down, looses all power. then i try to start it right away it wont start wants to start but sounds like it was out of gas, i wait 10 minutes turn the key back and forth a couple times and it starts right up. It doesnt happen all the time you never know when its gonna just shut down. i changed the ignition lock cylinder which came with 2 keys thinking that was the problem, cause i didnt have the original keys when i purchased this vehicle. its definately NOT my fuel pump. When i bought the truck the steering column cover was all loose and the dash board was loose...so we are thinking it has to do with the pass lock security system in the blazer...that the blazer was either a repo or bought at an auction for cheap..the mechanic told me that unless the service engine light is on cant do anything...my service engine light did come on and come to find out it only showed that my thermostat need to be replace. i know that the thermostat had nothing to do with the pass lock security system....Alot of people keep telling me this needs to be programmed
I replace the ignition lock cylinder ... this will require reprogramming the new switch with BCM which is a dealer fix. bypass the security function from the switch by inserting the same resistance value ( within 1% ) but this defeats the intended purpose of the anti-theft...also using a scan tool which only chevy dealers have.

your problem is either on your transponder or amplifer ring you need to get someone who can read your key or test your amplifer

I had the same problem when I replaced my multiswitch. I set off the "passlock 2" system that my blazer was equipped with because I didn't disconnect the battery before I took out the bad switch and put in a new one. That ended up blowing a fuse labeled "TBC." Its located in the fuse box in the engine compartment. Its a 10 amp. I know you said you checked all the fuses, but I would double check that one.

A used body control can be used in a vehicle other than the vehicle it was installed in. the body control module when first installed is programmed with the vehicle vin number. the vin number can not be changed was it was written to the BCM. the oprions can be always change in the BCM but not the VIN number. basically the used bcm you have installed has the vin number from the vehicle was installed in, now the vin number in the used BCM doesnt match all the other control modules